1. Field of the Invention
The present invention relates to an electronically controlled fuel injection system, more particularly to an electronically controlled fuel injection system for a gasoline engine having a fuel system for supplying fuel to an injector and a control system for controlling the fuel injection time for the injector in which the fuel flow from an electric fuel pump is calculated in accordance with different control variables for the engine so as to reduce the noise of the fuel pump and to econimize or save the consumption rate of the electric power.
2. Description of the Prior Art
In conventional electronically controlled fuel injection system, when a key switch, for instance, is turned on, a battery voltage is always applied to the fuel pump and an engine begins operating with full power. However, in this kind of system according to the prior art, the following problems occur;
(a) the noise produced by the fuel pump becomes relatively conspicuous because of the low engine noise during idling of the engine, (b) electric power is wasted because the pump is always operated at full power in spite of the small fuel injection amount required by the engine, (c) the fuel in the fuel tank is heated as some of the fuel is always returned to the fuel tank operated at full power through the peripheries of the engine even if the fuel consumption amount or rate of the engine is small, and (d) the number of rotations of the fuel pump is decreased when the battery voltage is excessively lowered at the time of low temperature starting of the engine, and the engine start becomes difficult due to the resultant low fuel pressure.